The objective is to better understand the functioning and capabilities of the human auditory system. One concern is with the abilities of the system to lateralize and to detect high-frequency signals. Recent research of ours and others has shown that, contrary to the so-called duplex theory of sound localization, human listeners can use interaural time differences to lateralize at high frequencies if the waveforms are complex (non-sinusoidal) so that there are interaural differences in envelope time. We plan to investigate various aspects of this ability by doing psychophysical research. Also of interest is whether the cue of envelope time difference can be used to advantage for signal detection. A second concern is with the auditory system's ability to suppress reverberation, an ability often characterized as the precedence effect. Reverberation suppression will be studied by manipulating signal duration, and the number, intensity, time delay, and azimuth of successive presentations of the same signal, while measuring the maximum delays that can be tolerated without producing a clear echo.